The purpose of the study is to investigate the relationship between environmental agents and reproductive health. Environmental agents of interest include exposure to chemicals such as polychlorinated biphenyls (PCBs), flame retardants, dioxins, bisphenol A, phthalates, pesticides, and metals like lead and cadmium. We are also interested in the relationship between reproductive health and lifestyle risk factors, such as exposure to environmental tobacco smoke. Enrollees are asked to participate in this study because they and their partner are patients of the MGH Fertility Center, trying to get pregnant, either naturally or by undergoing Intrauterine Insemination (IUI) and/or In Vitro Fertilization (IVF).